I have an Optiarc 7190 in a USB enclosure and a 7191S in the machine. I dont know what Optiarc/Sony did to the 7191, but the 7191 burns at MUCH lower speeds than the 7190 on the same media.

An example is my verbatim DL's. In the 7190, the disk shows at a maximum burn speed of 4x. The same disk (literally) in the 7191S shows 2.4x

Does anyone know what brand of Dual Layer DVD's can be purchased to burn at 8x speed on the 7191S over the net? I ask over the net because "look for made in malaysia" or "only if factory coded 8291" won't really be able to be checked.

I would go to their website and see if they have posted some media that they recommend and write speeds, if that's not posted you can email tech support. Unless you find a member here that has that particular drive, there's not much way to know what is in the firmware, or perhaps if the drive is supported by mediacodespeededit, then you can look and see what media is at what write speed. I hope this helps some.